Tube shield



Jan. 15, 1963- H. J. MURPHY 3,073,886

TUBE SHIELD Filed July 13, 1956 INVENTOR f/OWI/FbJ/WOAM ATTORNEY UnitedStates Patent 3,073,886 TUBE SHIELD Howard J. Murphy, 326 BallardvaleSt., North Wilmington, Mass. Filed July 13, 19-56, Ser. No. 597,728 5Claims. (Cl. 174-35) The present invention relates to an improvedelectrical shield construction, and more particularly to an improvedtube shield construction for association with electron discharge tubesor the like in electrical apparatus to avoid undesirable reactionsbetween the various elements thereof.

A wide variety of shielding means, generally identified as tube shields,have been employed heretofore in electrical apparatus, such as, forexample, radio sets, to dissipate electro-magnetic and electrostaticfields set up therein by the electron discharge tubes during theoperation of the apparatus. While such prior tube shields adequatelyperform their intended shielding function, such tube shields havepossessed many disadvantages which have been found objectionable.

One of the most common forms of tube shields heretofore employed hasconsisted of a simple can or cylinder which is secured to the chassis indetachable relationship therewith by a friction fit or similar fasteningmeans. When a tube is to be replaced in an apparatus employing theso-called can type tube shield, the tube shield is completely detachedfrom the chassis of the apparatus, after which the tube is thenreplaced. Oftentimes the repairman or technician performing theoperation will fail to replace the tube shield with a correspondingimpairment in the operation of the apparatus. Moreover, the failure toreplace the tube shield invariably results in the tube shield being lefton the chassis, thereby resulting in the likelihood of a shortcircuiting of the electrical apparatus. Another disadvantage with thecan type tube shield is that the continued insertion and withdrawal ofthe tube shield from time to time during the replacement results in aloose conection between the tube shield and the chassis. This willresult in a vibration of the tube shield, oftentimes not insuring apositive grounding of the shield to the chassis.

Another detachable form of the tube shield that has received widespreadusage is the so-called shaped shield. This type consists of twosymmetrically paired parts of sheet metal and shaped to fit closely tothe bulb of the tube. The paired parts are held together by a detachablering, a detachable collar, or various other forms of clamping andconnecting parts. Such shaped tube shields, in addition to the basicdisadvantages attendant to detachable tube shields in general, sufferfurther in that all tubes are not one size. Therefore, several differentsizes must be made and stocked, resulting in an unnecessary inventory.Moreover, the design and multiplicity of parts of the shaped tubeshields have resulted in a relatively high cost for such shields.

Some attempts have been made to eliminate these disadvantages attendantto the various forms of detachable tube shields fixedly securing thetube shields to the chassis. Such fixed tube shield constructions haveconsisted of two mating or paired parts, each of which are hingedlyconected at their bottom ends to one another or to the chassis. Toreplace a tube in an electrical apparatus employing such a construction,each of the mating parts is pivoted upwardly away from one another, thetube then replaced, and the component parts then pivoted inwardly to oneanother to envelope and shield the new tube. A principal disadvantagewith this type of tube shield is that it is extravagant of chassis spaceand does not permit the positioning of the tubes to the manufacturersrequire- 3,073,886 Patented Jan. 15, 1963 ments. Another disadvantagewith this form of shield is that latching or connecting means betweenthe mating parts to insure proper engagement of the shield parts must bepresent, thereby increasing the complexity and cost of such tubeshields. tube shields heretofore developed have met with very littlesuccess since compactness of design and simplicity of construction arenecessities in most electrical apparatus.

It is therefore a principal object in the elimination of the foregoingand related disadvantages to provide a new and novel tube shieldconstruction overcoming the disadvantages attendant to previouslyemployed tube shields.

Another object of the present invention is the provision of an improvedtube shield construction which will permit replacement of a tube moreeasily than with prior tube shields.

Yet another object of the present invention is the provision of animproved tube shield construction which will be permanently affixed tothe chassis, thereby insuring the proper functioning of the tube shieldat all times.

A further object of the present invention is the provision of animproved tube shield construction that requires a minimum amount ofchassis space.

A still further object of the present invention is the provision of animproved tube shield construction in which the component parts will bein proper engagement with one another at all times.

Another object of the present invention is the provision of an improvedtube shield construction that will remain in tight engagement and inproper grounded relationship with the chassis at all times.

A still further object of the present invention is the provision of animproved tube shield construction that is of extreme simplicity indesign and operation, and inexpensive to manufacture.

Other and additional objects will become apparent from the ensuingdescription taken in conjunction with the accompanying drawings.

Broadly stated, in the attainment of the foregoing related advantages, atube shield construction of the present invention comprises a metalsleeve means in the form of a longitudinally or axially compressibletelescoping helix and connecting means secured at the bottom end thereoffor securing same to a support.

To the accomplishment of the foregoing and related ends, the presentinvention then consists of the means hereinafter fully described andparticularly pointed out in the claims, the annexed drawing and thefollowing description setting forth in detail certain means in thecarrying out of the invention, such disclosed means i1- lustrating,however, but one of various ways in which the principle of the inventionmay be employed.

The present invention is illustrated by way of example in theaccompanying drawings, in which:

FIGURE 1 is a perspective view of a tube shield construction made inaccordance with the present invention in unattached relationship.

FIGURE 2 is a front elevation of the tube shield construction shown inFIG. 1 attached to a support and in operating relationship.

FIGURE 3 is a front elevation of the tube shield construction shown inFIGURE 2 in an axially compressed state to permit the withdrawal orreplacement of an electron discharge tube.

Reference is now to be had to the drawing wherein an illustrativeembodiment of a tube shield construction made in accordance with thepresent invention and generally designated by reference numeral 10 isshown. The tube shield construction 10 comprises a body portion 11 madein the form of an axially compressible helix which Therefore, thepermanently afiixed.

in its normal uncompressed state is of a height corresponding to that ofthe electron discharge tube to be shielded. The bottom edge of the bodyportion 11 is provided with securing means, such as a connecting tab 12,for securing the same to a support.

The body portion 11 may be made from any suitable strip metal stockcapable of being axially compressed or telescoped. As shown in FlGURE 1,the body portion 11 includes a first course 13 in which a portion of itsbottom edge is at right angles to the connecting tab 12, and will serveto engage the surface of the support properly. The second course 14 is acontinuation of the first course 13, and is in inclined relationshipthereto. The second course 14 is of a lesser diameter than that of thefirst course i3, and is in overlapping relationship thereto. The thirdcourse 15 likewise is inclined with respect to the second course 14, andis also of a lesser diameter, with the diameter of the fourth course 16being less than that of course 15, with each course lying in overlappinginclined relationship with one another to insure positive shielding.

The tube construction 1% is preferably formed by employing a piece ofmetal ribbon and angularly winding same upwardly so that it will be ofdiminishing scope in cross-section with the inside diameter of the finalcourse being greater than the tube diameter of the electron dischargetube. In this construction, a longitudinal or axial compression of theformed helix results in the body pordon-10 is a compressed state to aheight generally corresponding to the height or width of the metal stripemployed which will be ample to permit the replacement of a tube.

To secure the tube construction it} to a support 17, the

securing tab 12 is inserted in a slot immediately adjacent the socketopening and bent outwardly therefrom against the under surface of thesupport 17, as shown in FIG URES 2 and 3, thereby locking the firstcourse in tight relationship to the support. In its normal position thebody portion 11 will be in an unflexed or uncompressed state, and willbe of a height sufiicient to adequately shield the electron dischargetube 13. When it is desired to replace a tube, the fourth course 16 iscompressed downwardly toward the base 17, resulting in each of thecourses 1346 telescoping within one another until the body portion 11 isof a height corresponding to that of the first course. The tube is thengrasped, Withdrawn, and replaced, and the hand holding the body portion11 is then released. The body portion 1 will then snap back into itsoriginal position, as shown in FIG. 2, to-

provide the necessary shielding.

While in the illustrative embod ment the volute has its wider endsecured to the support 17, it will be apparent that the narrower end maybe so secured, as may be desirable for the conservation of space when anupwardly enlarging tube is to be shielded. However, when shieldingcylindrical tubes, it is preferable to have the narrower end of thevolute uppermost, as the volute can then most readily be collapsed withthe backs of the fingernails while the fingers grasp the tube to removeor insert it.

While there have been described herein what are at present consideredpreferred embodiments of the invention, itwill be obvious to thoseskilled in the art that modifications and changes may be made thereinwithout departing from the essence of the invention. It is therefore tobe understood that the exemplary embodiments are illustrative and notrestrictive of the invention, the

scope of which is defined in the appended claims, and that allmodifications that come within the meaning and range of equivalency ofthe claims are intended to be included therein.

I claim:

1. In an electrical apparatus having a support, a tube socket associatedwith said support for receiving an electron discharge tube therein and-a tube shield construction positioned adjacent said socket in shieldingrelation to a tube when positioned therein, the improved tube shieldconstruction comprising a sleeve member in the form of an axiallycompressible volute of conductive material having a plurality of wound,overlapping courses decreasing in cross section from the bottom to thetop and open at both ends thereof, and connecting means secured at thebottom end thereof for securing same to the support in said shieldingrelation.

2. The invention of claim 1 in which the bottom turn of said volute hasa bottom edge lying in a plane at right angles to the axis of thevolute.

3. In combination, a chassis, a socket secured thereto and a shield foran electronic component adapted to be mounted within said socket, saidshield surrounding said socket and comprising a helioally wound strip ofconductive metal, the adjacent turns of the helix being in overlappingrelation to provide a shield for said component, said shield beingaxially collapsible on application of pressure with the successive turnsnesting into adjacent turns, and mounting means for said shield securedthereto at the margin of at least one end thereof, said mounting meanscomprising at least one tang integrally extending from one edge of saidmetallic strip at the section thereof forming an end turn of said helix,an opening in said chassis adjacent said socket, said tang extendingthrough said opening and permanently securing said shield to saidchassis.

4. In combination, a chassis and a shield for an electronic componentcomprising a helically wound strip of metal, said shield beingcollapsible on application of pressure with successive turns nestinginto adjacent turns, and mounting means for said shield secured theretoat the margin of at least one end thereof, said mounting meanspermanently securing said shield to said chassis.

5. In combination, a chassis and a shield for an electronic componentcomprising a helically wound strip of metal, said shield beingcollapsible on application of pressure with successive turnsnesting intoadjacent turns, and mounting means for said shield secured thereto atthe margin of at least one end thereof, said mounting means comprisingtang means extending from one edge of said metallic strip at the sectionthereof forming an end turn of said helix, and tang receiving openingmeans in said chassis; said tang means extending through said openingmeans and permanently securing said shield to said chassis.

References Cited in the file of this patent UNITED STATES PATENTS1,049,199 Bowman Dec. 31, 1912 1,270,462 Thueringer June 25, 19182,488,244 Shea Nov. 15, 1949 2,646,460 Del Camp July 21, 1953

3. IN COMBINATION, A CHASSIS, A SOCKET SECURED THERETO AND A SHIELD FORAN ELECTRONIC COMPONENT ADAPTED TO BE MOUNTED WITHIN SAID SOCKET, SAIDSHIELD SURROUNDING SAID SOCKET AND COMPRISING A HELICALLY WOUND STRIP OFCONDUCTIVE METAL, THE ADJACENT TURNS OF THE HELIX BEING IN OVERLAPPINGRELATION TO PROVIDE A SHIELD FOR SAID COMPONENT, SAID SHIELD BEINGAXIALLY COLLAPSIBLE ON APPLICATION OF PRESSURE WITH THE SUCCESSIVE TURNSNESTING INTO ADJACENT TURNS, AND MOUNTING MEANS FOR SAID SHIELD SECUREDTHERETO AT THE MARGIN OF AT LEAST ONE END THEREOF, SAID MOUNTING MEANSCOMPRISING AT LEAST ONE TANG INTEGRALLY EXTENDING FROM ONE EDGE OF SAIDMETALLIC STRIP AT THE SECTION THEREOF FORMING AN END TURN OF SAID HELIX,AN OPENING IN SAID CHASSIS ADJACENT SAID SOCKET, SAID TANG EXTENDINGTHROUGH SAID OPENING AND PERMANENTLY SECURING SAID SHIELD TO SAIDCHASSIS.